Welding materials and upholstered or other fabric structures comprising same



April 1950 E. w. WEITZEL ,932,121

WELTING MATERIALS AND UPHOLSTERED OR OTHER FABRIC STRUCTURES COMPRISING SAME Filed Aug. 1. 1956 INVENTOR EDWARD W. WEITZEL ATTORNEYS 2,932,121 WELDING MATELS AND UPHOLSTERED OR OTHER FABRIC STRUCTURES COMPRISING SAME Edward W. Weitzel, Hickory, N.C., assignor to Shuford Mills, Hickory, N.C., a corporation of North Carolina Application August 1, 1956, Serial No. 601,550 7 Claims. (1. 45-138) This invention relates to welting materials,i.e.', prod-- Field of invention Most pieces of upholstered furniture have one or more exposed edges which are finished with welting. Thus, in holstered articles, there are usually one or more edges along which two separate Sections of fabric are joined where a cord-like material is sewed or otherwise fastened to the edge to cover up the stitched junction between the two separate fabric sections. Such construction is called a welted edge and serves several purposes. First, it protects the stitching which holds the fabric sections to gether against wear and helps to prevent the seam from. being split open. In addition, it strengthens the seam by adding additional high tensile strength material along the edge which usually is subjected to greater pulling forces than other sections of the upholstered structure. Finally, the welting serves to create a better appearing product, since it covers up stitching and seams which would otherwise be unsightly.

The use of welting materials is by no means limited to the fabrication of upholstered furniture and a large variety of other fabric structures also are usually made with welted edges. For example, many pieces of clothing, such as jackets, coats, shoes and caps have edges that are finished with welting. Other well known products made with welted edges include awnings, seat covers, canvas-covered lawn furniture, and drapes.

Welting materials are also referred to in the trade as seaming cores and edgings and such terms include ,socalled seat edge, spring edge and formed edge. Some complicated or special products have been created and sold in the past for use as welting material, but the majority of welted edges are formed by folding a narrow strip of fabric around a small cord-like core and then stitching the overlapped free ends of the fabric strip into the seam which defines the edge to be welted. Considering the many types of products which are formed with welted edges and the total length of such edges in each individual article, it can be appreciated that tremendous quantities of welting core material are consumed each .year. 'In view of the large quantities required, and also because welting is only a very minor portion of any given fabric article, it is necessary that welting core material be very inexpensive.

Quite a variety of materials have been employed and tested in making welting core, but at the present time, such core is made for the most part of twisted kraft paper, e.g., see US. Patents 1,370,690, 1,846,369, and 2,282,168.

2,932,12i Patented Apr. 1 2, 1960 Other welting core materials include the type made of a cotton roving center with a braided cotton thread cover,

and the type made of a cellulose wadding center and a glass fiber braided cover, e.g., see U.S. 2,557,343. Also, strips of rubber or sponge rubber have been proposed for use in the formation of finishing strips for upholstery or the like, e.g., see US. Patents 1,911,649 and 2,243,743, However, although such a variety of products has been suggested and tested for use as welting cores, probably better than of the market is supplied primarily by twisted kraft paper and secondarily by the braided cotton covered roving, because the suggested substitutes have been found unsatisfactory due to lack of tensile strength,-

inability to properly conform to the edges into which they, are incorporated, or for other reasons.

Even though the twistedkraft cord and braided roving are so widely used as core materials for welting, it is well known that they possess certain inherent defects which have caused the trade to try for a long time to find suitable substitutes which would possess their advantages as welting core, and at the same time eliminate their disadvantages. For example, such core materials are not easily compressed, so that they create stiff, non-cushioned welted edges. Also, they cannot be stretched to any appreciable extent, so they do not conform too well to various contours, particularly square corners. As a result, the formation of welted edges using a twisted kraft paper or braided roving core often results in bunching or wrinkling of the welting, especially at sharp or square corners. Furthermore, these core materials will shrink when dried after being wet, and this creates severe edge wrinkling problems, particularly in garments which are washed, or with awnings or lawn furniture which are subjected to alternate wetting and drying. Finally, twisted kraft cord or braided cotton roving both have a relatively rough surface which cuts or damages the fingers of upholsterers or other persons when they use such core material.

Objects A principal object of this invention is the provision of a new type of core material for use in the formation of welted edges, and the provision of new welting material comprising such new welting core. Further objects include:

(1) The provision of welting core which is firm, and, yet relatively compressible, so that a cushioned welted edge can be formed with it.

(2) The provision of welting core which can be elongated an appreciable amount, but which, at the same time has good tensile strength and is resilient, so that it will return after elongation to its original shape, whereby the core material can adjust itself to the contour of the article into which it is incorporated or sewed, to always give a straight, unwrinkled seam or edge.

(3) The provision of welting material which can be I Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specit' 3 ie examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

General description These objects are accomplished according to the present invention by formation of a waiting core which is shrinkproof, resilient and capable of elongation without breakage to proportion itself to the contour of the article into which it is incorporated from foamed, flexible, resilient plastic material. Preferably, the new Welting core is made in the form of a flexible rod between about and inch in diameter from plasticized vinyl chloride polymer which has dispersed throughout a multiplicity of small pores, creating a resilient, sponge-like structure. Such core material is then combined with a cover to form welting material, and this inturn is incorporated in fabric structures to create welted edges.

A more complete understanding of the new welting materials of this invention and their method of use in the formation of fabric articles having welted edges may be obtained by reference to the attached drawings, in which:

Fig. l is a plan view of a short strip of welting core in accordance with the present invention;

Fig. 2 is an enlarged sectional end view of welting core, such as shown in Fig. 1;

Fig. 3 is a fragmentary sectional view of the edge of a fabric structure which has been finished with new welting material of this invention;

Fig. 4- 'is a fragmentary sectional end view of another form of fabric structure which incorporates the new'welting core of this invention and;

Fig. 5 is a fragmentary view of the appearance of the new welting core when it is bent in a 90 angle.

Detailed description Referring in detail to the drawings, the new welting core 2 comprises a flexible rod of plastic material 4, which includes a plurality of small pores 6, which are relatively small with respect to the diameter of the rod, and are of such multiplicity and distribution that they give the plastic material 4 a sponge-like or foamed structure.

in order to be of any use as a welting core, the rod 2 must be strong, and preferably should have a tensile strength of at least 500 pounds per square inch. Furthermore, although the rod may be made in a variety of sizes, it should have sufliciently large diameter to have a breaking strength of 15 pounds or more, but not so large as to be unusable to form a welted edge. Rods having a diameter between about and A; inch are preferred.

The new welting core should he capable of elongating at least (preferably 10% to 50%) and sufiiciently resilient that when so elongated, it will return substantial- 1y to its original length upon release of the elongation force. Such elongation and resilient properties of the new welting cores is due partially to the foamed or spongelike structure, but also the plastic material 4 used in the fabrication of the new cores should itself be resilient and flexible. Several plastic materials possess, or can be compounded to possess, the required qualities for use in forming the new welting materials. For example, such plastic as elastic types of polyethylene and polyester resins, flexible forms of nylon and polyurethane resins, or other plastics of similar characteristics may be employed. However, it has been found that the most desirable combination of resiliency, elongation and cushioning effect, plus shrink-proofncss and weather resistance is obtained through the use of flexible formulations of vinyl plastics, especially plasticized vinyl chloride polymers, e.g., vinyl chloride copolymers containing small amounts of vinyl acetate, or polyvinyl chloride.

As is well known in the plastics art, many plastic materials require use of plasticizers in order to create a final plastic product which is flexible and resilient. This is particularly true of vinyl chloride polymers which without plasticizer are relatively stiff and inflexible. Many different plasticizers are known and may be used, but the so-called hot stretch plasticizers are particularly desirable, and dioctyl phthalate and dibenzyl benzoate are specific examples of this type of plasticizer. Of course, the amount of plasticizer used will depend upon the particular plasticizer chosen for use, and also the specific resin used in making the welting cores. Those skilled in the art will know how to formulate suitable plastic compositions for the purpose when advised of the desired elongation, tensile and resilient properties, as outlined above. Furthermore, as is also well known in the plastics field, there are several forms of usable plastics, e.g., flexible grades of nylon and self-plasticized polyesters, which'havc the required flex, tensile, and resiliency qualities to be used without plasticizers.

Although it would be possible, by a casting operation, to produce foamed plastic rod for use as welting core in accordance with this invention, the preferred method of making the core material is by extrusion. This is accomplished by forcing a suitably compounded plastic mass in a fluid state through a properly sized extrusion die from a screw-stulfer extruder or other suitable extrusion device. The sponge-like or foamed structure in the resulting rod, is obtained by having in the plastic as it extrudes from the die a so-called blowing agent which, upon the release of pressure from the extruded mass upon leaving the die, causes the plastic to expand into a porous, sponge-like structure. in some cases, the blowing agent may be formed in situ by reaction of ingredients used in the formation of the plastic, but in the case of the preferred vinyl chloride polymers, and the majority of other materials, a blowing agent must be added to the plastic mixture when it is compounded. These blowing agents are materials which decompose under the heat employed in the extrusion operation and create gaseous products which bring about the expansion effect. A wide variety of different blowing agents have been developed, and substantially any of these can be used in forming the new core materials. Organic blowing agents, e.g., dinitroso pentamethylene tetramine, are satisfactory, but better results with less expense have been obtained in the formation of the new products by using inorganic blowing agents, such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and ammonium sesquicarbonate. The blowing agent is usually employed in about 0.5 to 25% by weight of the total plastic mass, but the exact amount is governed to some extent by the particular plastic and plasticizer used. As a general rule, the quantity of blowing agent is controlled to give a final product which constitutes between about 10 and by volume of solid plastic, the remainder of the volume being made up of the pores which create the sponge-like structure.

Method of use and resulting structures With full description of the new welting cores as given above, it is possible to consider the manner in which these cores are used to form welting materials, and to finish the edges or other portions of fabric articles. Actually, the use of the new cores generally follows established welting procedure, e.g., operations used with twisted kraft core. However, the use of the new foamed plastic core in forming welted edges differs from welting operations known heretofore because the resilient and elongating properties of the new core material enables it to proportion itself to a given contour when installed, sewed or cemented into or along an edge. Thus, in contrast to such non-elongatable materials as twisted kraft. the new welting core can be appreciably stretched, and when so stretched, the core reduces slightly in diameter. This enables it to slip along through the surrounding fabric or cover, permitting an adjustment of the core along the finished edge to be obtained. As is well known by upholsterers and other fabric finishers, it is not possible in installing welting to keep a constantly even tension upon the welting material or other fabric being joined. This causes bunching up where twisted kraft or similar material has been used in the past as the core for forming the welted edge. In contrast, the welting core of this invention, due to its inherent resilient and elongation properties, may adjust to the differences in tension created during the finishing operation and create a finished edge in which the tension in the core material is substantially evenly distributed along the entire length of the complete welted edge.

Fig 3 illustrates the usual wayin which the welting cores and materials of this invention are employed. The fabric article 8, which is to be provided with a welted edge, includes two separate sections and 12 of fabric to be joined. A narrow strip of fabric 14, i.e., the cover, which usually is cut from the same material as sections 10 and 12, although it may be different in color and texture if special edge effects are desired, is folded tightly around the welting core 16. The free ends 18 and 20 of the fabric strip 14 are then overlapped and inserted between the abutting edges 22 and 24 of fabric sections 10 and 12 respectively. The juxapositioned edges 18 to 24 are then joined together, such as by stitching 26.

It will be understood that the resulting welt edge as shown in Fig. 3 could be a portion of an upholstered furniture piece. an article of clothin such as a jacket or cap. an awning, or any other fabric article which would include an edge along which two separate sections of fabric are to be ioined.

As previously indicated, one annoying problem which has characterized the use of twisted kraft welting core has been the bunching or wrinkling at sharp or square corners. This problem is not experienced with the new welting cores of this invention. This is apparently due to the manner in which the new core material bends around a corner. as shown in Fig. 5. Thus. the foamed plastic core 2, when bent through a 90 angle collapses on the inside corner 28 to give a perfectly square configuration presenting a smooth outside bent edge 30. As a consequence. upholstered furniture or other articles can be made with these new weltin materials without bunching at sharp corners or wrinkling along a welted edge occurring. as is often noticed in upholstered furniture or the like made rior to this present invention.

Another method of use of the new welting cores is illustrated in Fig. 4. This type of construction which, for example, might be employed in the formation of plastic seat covers or in ornamenting the backs of plastic covered chairs or automobile side panels, comprises two separate sheets of plastic material 32 and 34. These are joined together at points 36 to form a laminar structure by heat sealing the points of contact. Between these separate points 36, there are positioned between the separate plastic sheets 32 and 34, sections of the welting core 16. This type of construction creates the so-called "rib effect often used today for ornamental purposes in automobile seat covers and side panels, but it is also usable for edge protection purposes or the like.

It should be pointed out that although the materials of which this invention is concerned are most commonly referred to as welting materials, sometimes the term piping" is employed to refer to such products, especially in the garment trade. Hence, the single term welting" has been used herein to encompass also piping." Furthermore, whereas the new core materials of the invention have been described and illustrated as solid rods or rod-like structures, it is possible to form them with small hollow centers, giving a product more in the nature of a tube than a solid rod. Accordingly, the single term rod has been used herein to encompass the rod like structures whether made solid or with a hollow center.

I claim:

1. A welting core which is shrink-proof, resilient and capable of conforming accurately to the contour ofthe article into which it is incorporated Without wrinkling,

or forming bulges, consisting of a flexible rod having a tensile strength of at least 500 pounds per square inch between about and% inch in diameter of plasticized vinyl chloride polymer having dispersed throughout a multiplicity of small pores forming a resilient, spongelike structure.

2. A welting core as claimed in claim 1 wherein said polymer comprises between about 10 and by volume of the core.

3. Welting for finishing the edge of a fabric structure comprising a core consisting of a small diameter rod having a tensile strength of at least 500 pounds per square inch of foamed resilient, flexible plastic and a fabric cover folded around the core, tightly enclosing the core, the overlapping edges of the fabric cover forming a means for attachment of the welting to the structure to be finished therewith.

4. Welting as claimed in claim 3 wherein said rod is composed of plasticized polyvinyl chloride which contains a multitude of small pores in the form of a spongelike structure.

5. A ribbed section of plastic upholstery comprising a plurality of sheets of flexible plastic material laminated together, there being at least one welting core consisting of a small diameter rod having a tensile strength of at least 500 pounds per square inch of foamed plasticized vinyl chloride polymer enclosed between said sheets forming a rib in the laminar structure.

6. As a core for welting, a rod between about $4 and $4; inch in diameter consisting of plasticized vinyl chloride polymer having dispersed throughout a multiplicity of small pores which constitute about 30 to by volume of the rod, the rod having a tensile strength of at least about 500 pounds per square inch.

7. Welting for finishing the edge of a fabric structure comprising a shrink-proof, resilient welting core capable of conforming accurately to the contour of said structure without wrinkling or forming bulges, said core being a flexible rod having a tensile strength of at least 500 pounds per square inch between about 7 and ,4; inch in diameter of flexible plastic material having dispersed.

throughout a multiplicity of small pores forming a resilient, sponge-like structure.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A WELTING CORE WHICH IS SHRINK-PROOF, RESILIENT AND CAPABLE OF CONFORMING ACCURATELY TO THE CONTOUR OF THE ARTICLE INTO WHICH IT IS INCORPORATED WITHOUT WRINKING OF FORMING BULGES, CONSISTING OF A FLEXIBLE ROD HAVING A TENSILE STRENGTH OF AT LEAST 500 POUNDS PER SQUARE INCH BETWEEN ABOUT 1/16 AND 1/2 INCH IN DIAMETER OF PLASTICIZED 